Each time a Dragon Breathes Fire, it expends a point of Will. Treat the Dragon's fiery breath as a bow with a range of 12". If the shot hits, the target and all models (friend and foe) within 2" suffer a Strength 10 hit. Any model that suffers an unsaved Wound (Fate may still be taken) from a Dragon's Breathe Fire is automatically slain.
12"
10
